TCRγ rearrangements at the diagnosis and during TKI therapy. Clonality of the lymphocytes was determined by PCR and gel analysis with the use of 12 primer pairs for the TCR γ gene rearrangements and 6 primer pairs for TCR δ gene rearrangements. After PCR amplification and heteroduplex treatment, the PCR products were separated by electrophoresis on a 5% Criterion gel. Gels were stained with EtBr and visualized with ultraviolet illumination. (A) Dasatinib-treated patient with LGL lymphocytosis showing clonal PCR products (white arrow) of the primer pair TCRγ 12 at diagnosis and during dasatinib therapy. Lane 2 indicates at diagnosis; lane 3, 6 months after start of dasatinib therapy during lymphocytosis; lane 4, pool of healthy controls showing polyclonal smear; lane 5, water control. (B) Imatinib-treated patient without lymphocytosis showing clonal PCR product (white arrow) of the primer pair TCRγ 6 at diagnosis. After 12 months of imatinib therapy, no clonal band was visible. Lane 2 indicates at diagnosis; lane 3, 12 months after start of imatinib therapy; lane 4, pool of healthy controls showing polyclonal smear; lane 5, water control. Positive findings were confirmed with sequencing. Vertical lines have been inserted to indicate a repositioned gel lane (DNA ladder).